The history panel keep track of all the actions that are made in synfigstudio during edition a file. This history list is empty for a new clean file and also when the file already existsand is opened, so it is not saved with the file (is it worth to save it in the sifz file?).
When a single user operation produces a lot of actions (tipically when manipulating lots of ducks at the same time) all those common actions are grouped into a expandable one. See the small triangle in the image sample. By clicking on the smal triangle you can expand the grouped actions and access them individually.
The check box column is used to disable speciphic actions without re run backward all the action list. So if you want to redo or undo an speciphic action (or group of actions) just click on the check box.
The (JMP) column is used to redo or undo all the actions from the current status to the action you where you click on the (JUMP) word.
The Action column makes a description of the action itself. The verbosity of the action description cannot be controlled but it was designed to be a compromise between its lenght (readability) and its meaning.
The undo and redo buttons undo or redo a single action each time they are pressed.
Finnaly the Clear Undo and Clear Redo cleans the history list of actions of Undo or Redo. The Clear Undo and Clear Redo actions cannot be undone.